Category: Nevin Manimala

Appl Opt. 2023 Feb 20;62(6):A1-A11. doi: 10.1364/AO.473632.

ABSTRACT

Velocity measurement has a high application value in hydrological monitoring and flood disaster warning. The long-distance laser Doppler water flow velocimetry technology has the advantage of strong anti-interference ability and high spatial resolution, and it can realize the high-precision measurement of water flow velocity. Because water flow has low reflectance characteristics, how to extract Doppler frequency from weak non-stationary coherent signals is a crucial problem to be solved to realize long-distance water flow velocity measurement. However, the classical method requires the time domain signal to have high stationarity and is not suitable for processing the coherent signal in the water flow velocity measurement. Aiming at this problem, we proposed a water flow velocimetry method based on adaptive Gaussian weighted integral (AGWI). First, the spectral characteristics of the coherent signal are analyzed in detail, and a statistical model of weak non-stationary signals is established. A second-order Kaiser self-multiplication window (KSMW) is designed to suppress spectral leakage for the asynchronously sampled data. Then, an adaptive homogenization power spectral subtraction (AHPSS) is designed to reduce system noise. Finally, the Doppler spectrum reconstruction and Doppler frequency estimation are performed using the AGWI method to obtain the Doppler frequency, which is further processed to get the water flow velocity. The experimental results show that the method proposed in this paper can achieve accurate and stable measurement of river surface velocity under long-distance conditions.

PMID:36821294 | DOI:10.1364/AO.473632

Appl Opt. 2023 Feb 10;62(5):1253-1262. doi: 10.1364/AO.475825.

ABSTRACT

The fast-Fourier-transform-based filtering method for phase screen generation remains popular for numerical simulation of optical propagation through turbulence; however, these screens inherently underrepresent the spectral density at low wavenumbers. Here, the “Z-tilt” approach is explored to augment the spectral density at low wavenumbers by adding a random phase tilt, which is derived from the wavefront phase statistics of a Zernike polynomial basis. This approach is computationally efficient and can be applied to any statistically homogeneous and isotropic refractive index field. An analytic result is provided for the von Kármán spectrum with finite outer scale. In a quantitative comparison with phase screens compensated for using a common subharmonic approach, the Z-tilt method shows the best agreement with the analytical structure function when the outer scale is greater than about three times the screen dimension. For outer scales of the order of the screen dimension, the subharmonic and a modified Z-tilt method give the most accurate results. A propagation simulation demonstrates that the aperture-averaged angle-of-arrival variance is accurately predicted using the Z-tilt method.

PMID:36821225 | DOI:10.1364/AO.475825

J Opt Soc Am A Opt Image Sci Vis. 2023 Feb 1;40(2):285-293. doi: 10.1364/JOSAA.477639.

ABSTRACT

We show that quantum detector tomography can be applied to the human visual system to explore human perception of photon number states. In detector tomography, instead of using very hard-to-produce photon number states, the response of a detector to light pulses with known photon statistics of varying intensity is recorded, and a model is fitted to the experimental outcomes, thereby inferring the detector’s photon number state response. Generally, light pulses containing a Poisson-distributed number of photons are utilized, which are very easy to produce in the lab. This technique has not been explored to study the human visual system before because it usually requires a very large number of repetitions not suitable for experiments on humans. Yet, in the present study we show that detector tomography is feasible for human experiments. Assuming a simple model for this accuracy, the results of our simulations show that detector tomography is able to reconstruct the model using Bayesian inference with as few as 5000 trials. We then optimize the experimental parameters in order to maximize the probability of showing that the single-photon accuracy is above chance. As such, our study opens the road to study human perception on the quantum level.

PMID:36821198 | DOI:10.1364/JOSAA.477639

J Opt Soc Am A Opt Image Sci Vis. 2023 Feb 1;40(2):237-258. doi: 10.1364/JOSAA.472553.

ABSTRACT

Analysis of visual texture is important for many key steps in early vision. We study visual sensitivity to image statistics in three families of textures that include multiple gray levels and correlations in two spatial dimensions. Sensitivities to positive and negative correlations are approximately independent of correlation sign, and signals from different kinds of correlations combine quadratically. We build a computational model, fully constrained by prior studies of sensitivity to uncorrelated textures and black-and-white textures with spatial correlations. The model accounts for many features of the new data, including sign-independence, quadratic combination, and the dependence on gray-level distribution.

PMID:36821194 | DOI:10.1364/JOSAA.472553

Alzheimer Dis Assoc Disord. 2023 Jan-Mar 01;37(1):35-41. doi: 10.1097/WAD.0000000000000542. Epub 2023 Feb 23.

ABSTRACT

INTRODUCTION: Atherosclerosis has been shown to impact cognitive impairment, with most of the evidence originating from European, African, or East Asian populations that have employed carotid intima-media thickness (cIMT) as a biomarker for atherosclerosis. Vascular disease is related to dementia/cognitive decline. There is no community-based study from India that has looked at the association of cIMT with cognitive performance.

METHODS: In this cross-sectional study between December 2014 and 2019, we recruited 7505 persons [(mean age 64.6 (9.2) y) and 50.9% women] from a community-dwelling population in New Delhi. These persons underwent carotid ultrasound to quantify cIMT and a cognitive test battery that tapped into memory, processing speed, and executive function. We also computed the general cognitive factor (g-factor), which was identified as the first unrotated component of the principal component analysis and explained 37.4% of all variances in the cognitive tests. We constructed multivariate linear regression models adjusted for age, sex, education, and cardiovascular risk factors. Additional adjustment was made for depression, anxiety, and psychosocial support in the final model.

RESULTS: We found a significant association of higher cIMT with worse performance in general cognition (β=-0. 01(95% CI: -0.01; -0.01); P<0.001), processing speed (β=-0.20; 95% CI: -0.34; -0.07); P=0.003), memory (β=-0.29; 95% CI: -0.53; -0.05); P=0.016), and executive function (β=-0.54; 95% CI: -0.75; -0.33); P=<0.001). There was no statistically significant association of cIMT with Mini-Mental Status Examination score (β=0.02; 95% CI: -0.34; 0.40; 0.89).

CONCLUSION: The cross-sectional study found significant associations of increased cIMT with worse performance in global cognition, information processing, memory, and executive function.

PMID:36821176 | DOI:10.1097/WAD.0000000000000542

Appl Opt. 2023 Feb 1;62(4):844-860. doi: 10.1364/AO.478668.

ABSTRACT

This study proposes a color image encryption method combining Fresnel diffraction, multi-phase retrieval, and hyperchaotic mapping in two stages. First, the color image is converted into an amplitude-type computer-generated hologram (CGH) that overlaps in the frequency domain and separates in the spatial domain. The Gerchberg-Saxton (GS) multi-phase retrieval algorithm encrypts the CGH into a meaningless ciphertext in the second stage, scrambling/diffusing it further using four random sequences generated from the Lorenz hyperchaotic system. The experiment on public color images shows that the decrypted color images are highly consistent with plaintext images. This method’s key has a large space (approximately 10^∧301) and a small volume. Slight changes to the plaintext completely alter the ciphertext, and its pixel values are statistically independent, thus securing the proposed method against chosen-plaintext attacks and chosen-ciphertext attacks.

PMID:36821148 | DOI:10.1364/AO.478668

J Urol. 2023 Feb 23:101097JU0000000000003390. doi: 10.1097/JU.0000000000003390. Online ahead of print.

ABSTRACT

PURPOSE: Although Children’s Oncology Group renal tumor protocols mandate lymph node sampling (LNS) during extirpative surgery for pediatric renal tumors, LNS is often omitted or low yield. Concerns over morbidity associated with extended LNS have led to hesitancy in adopting a formal LNS template. We hypothesized that complications in children undergoing LNS for renal tumors would be rare, and not associated with the number of LNs sampled.

METHODS: A single-institution, retrospective review of patients aged 0-18yrs undergoing extirpative renal surgery with LNS for a suspected malignancy between 2005-2019 was performed. Patients with 0 or an unknown number of LNs sampled or <150 days of follow-up were excluded. A “clinically significant” (CS) complication was defined as any Clavien-Dindo complication ≥ III, small bowel obstruction (SBO), chylous ascites, organ injury, or wound infection. The number of LNs sampled and its influence on the odds of experiencing a CS complication was examined.

RESULTS: 144 patients met inclusion criteria. Median patient age was 38 months. Twenty-one patients (15%) had a CS complication, the most common of which was ileus/SBO (n = 16). In a multivariable analysis, increased LN yield was not found to influence the odds of experiencing a CS complication (P = .6).

CONCLUSIONS: In this cohort, there was no statistically significant difference in CS complications in patients who underwent more extensive LNS during surgery for a suspected malignant pediatric renal tumor. Future studies on protocol adherence, staging accuracy, and survival trends using a LNS template in these patients should be performed.

PMID:36821137 | DOI:10.1097/JU.0000000000003390

JAMA Otolaryngol Head Neck Surg. 2023 Feb 23. doi: 10.1001/jamaoto.2022.5186. Online ahead of print.

ABSTRACT

IMPORTANCE: Clear surgical margins reduce the risk of local recurrence, improve survival, and determine decision-making with regard to adjuvant treatment of squamous cell carcinoma of the head and neck (SCCHN). However, the definitions of clear, close, or positive surgical margins vary in both the literature and in practice.

OBJECTIVE: To examine whether the association between surgical margin distance and survival varies by primary tumor site.

DESIGN, SETTING, AND PARTICIPANTS: This was a secondary analysis of a multi-institutional, multinational randomized clinical trial. The trial enrolled patients from January 22, 2007, to March 29, 2013, with stage II to IVA resected SCCHN with extranodal extension (ENE) or positive margins (<5 mm from invasive tumor to the resected margin). The current analysis included those patients with known ENE and margin status and was conducted from April 29, 2022, to December 19, 2022.

INTERVENTIONS: Patients received adjuvant chemoradiotherapy plus either placebo or lapatinib.

MAIN OUTCOMES AND MEASURES: Overall survival (OS) was calculated to examine association with surgical margin distance, primary site, and survival, with stratification by ENE status.

RESULTS: Among 688 patients enrolled in the trial, 630 patients with known ENE and margin status were included. Exact patient ages were not made available; 523 (83%) patients were male, and 415 (66%) patients were White. Patients with 1 high-risk feature (positive margins or ENE) had significantly better OS vs 2 high-risk features (hazard ratio [HR], 0.65; 95% CI, 0.49-0.87), although most other results were not statistically significant. For example, in the cohort with ENE-negative disease, multivariable adjusted analysis showed nonsignificant improvements with shorter surgical margin distance (1- to 5-mm margins), and no association with OS was found in the cohort with ENE-positive status (either >5 mm margins or 1-5 mm margins). The association between survival and margin distance varied based on primary site, human papillomavirus (HPV) status, and ENE status. For example, HPV-positive status was associated with a significant and clinically meaningful increase in survival (adjusted HR, 0.33; 95% CI, 0.11-0.97). The improvement was greatest, although not significantly so, in patients with ENE- and HPV-negative oropharynx (OP), hypopharynx (HP), and larynx cancer (HR, 0.57; 95% CI, 0.30-1.10). No survival benefit was seen in ENE-negative oral cavity cancer (HR, 0.89; 95% CI, 0.45-1.77), nor was an association observed between margins and OS in HPV-positive OP cancer.

CONCLUSIONS AND RELEVANCE: In this secondary analysis of a randomized clinical trial, the presence of high-risk features (extranodal extension, positive margins, or both) was associated with worse survival; longer survival was observed with greater surgical margin distance among patients with oral cavity tumors and human papillomavirus-negative tumors of the OP, larynx, or HP. No other significant differences were found. These findings support variable interpretation of surgical margin distance based on the primary site and HPV status.

TRIAL REGISTRATION: ClinicalTrials.gov Identifier: NCT00424255.

PMID:36821132 | DOI:10.1001/jamaoto.2022.5186

JAMA Netw Open. 2023 Feb 1;6(2):e230070. doi: 10.1001/jamanetworkopen.2023.0070.

ABSTRACT

IMPORTANCE: Conditional cash transfers (CCTs) have been consistently associated with improvements to the determinants of maternal health, but there have been insufficient investigations regarding their effects on maternal mortality.

OBJECTIVE: To evaluate the association between being a Bolsa Família program (BFP) beneficiary and maternal mortality and to examine how this association differs by duration of BFP receipt, maternal race, living in rural or urban areas, the Municipal Human Development Index (MHDI), and municipal primary health care coverage.

DESIGN, SETTING, AND PARTICIPANTS: This cross-sectional analysis was nested within the 100 Million Brazilian Cohort. Girls and women aged 10 to 49 years (hereinafter referred to as women) who had at least 1 live birth were included, using data from Brazilian national health databases linked to the 100 Million Brazilian Cohort (January 1, 2004, to December 31, 2015). Propensity score kernel weighting was applied to control for sociodemographic and economic confounders in the association between BFP receipt and maternal mortality, overall and stratified by different subgroups (race, urban or rural area, and MHDI), and duration of BFP receipt. Data were analyzed from July 12, 2019, to December 31, 2022.

MAIN OUTCOME(S) AND MEASURES: Maternal death.

RESULTS: A total of 6 677 273 women aged 10 to 49 years were included in the analysis, 4056 of whom had died from pregnancy-related causes. The risk of maternal death was 18% lower in women who received BFP (weighted odds ratio [OR], 0.82 [95% CI, 0.71-0.93]). A longer duration receiving BFP was associated with an increased reduction in maternal mortality (OR for 1-4 years, 0.85 [95% CI, 0.75-0.97]; OR for 5-8 years, 0.70 [95% CI, 0.60-0.82]; OR for ≥9 years, 0.69 [95% CI, 0.53-0.88]). Receiving BFP was also associated with substantial increases in the number of prenatal appointments and interbirth intervals. The reduction was more pronounced in the most vulnerable groups.

CONCLUSIONS AND RELEVANCE: This cross-sectional analysis nested within the 100 Million Brazilian Cohort found an association between BFP receipt and maternal mortality. This association was of greater magnitude in women with longer exposure to BFP and in the most vulnerable groups. These findings reinforce evidence that programs such as BFP, which have already proven effective in poverty reduction, have great potential to improve maternal survival.

PMID:36821115 | DOI:10.1001/jamanetworkopen.2023.0070

JAMA Netw Open. 2023 Feb 1;6(2):e230569. doi: 10.1001/jamanetworkopen.2023.0569.

ABSTRACT

IMPORTANCE: Cardiotoxicity is a serious adverse effect that can occur in women undergoing treatment for breast cancer. Identifying patients who will develop cardiotoxicity remains challenging.

OBJECTIVE: To identify, describe, and evaluate all prognostic models developed to predict cardiotoxicity following treatment in women with breast cancer.

EVIDENCE REVIEW: This systematic review searched the Medline, Embase, and Cochrane databases up to September 22, 2021, to include studies developing or validating a prediction model for cardiotoxicity in women with breast cancer. The Prediction Model Risk of Bias Assessment Tool (PROBAST) was used to assess both the risk of bias and the applicability of the prediction modeling studies. Transparency reporting was assessed with the Transparent Reporting of a Multivariable Prediction Model for Individual Prognosis or Diagnosis (TRIPOD) tool.

FINDINGS: After screening 590 publications, we identified 7 prognostic model studies for this review. Six were model development studies and 1 was an external validation study. Outcomes included occurrence of cardiac dysfunction (echocardiographic parameters), heart failure, and composite clinical outcomes. Model discrimination, measured by the area under receiver operating curves or C statistic, ranged from 0.70 (95% IC, 0.62-0.77) to 0.87 (95% IC, 0.77-0.96). The most common predictors identified in final prediction models included age, baseline left ventricular ejection fraction, hypertension, and diabetes. Four of the developed models were deemed to be at high risk of bias due to analysis concerns, particularly for sample size, handling of missing data, and not presenting appropriate performance statistics. None of the included studies examined the clinical utility of the developed model. All studies met more than 80% of the items in TRIPOD checklist.

CONCLUSIONS AND RELEVANCE: In this systematic review of the 6 predictive models identified, only 1 had undergone external validation. Most of the studies were assessed as being at high overall risk of bias. Application of the reporting guidelines may help future research and improve the reproducibility and applicability of prediction models for cardiotoxicity following breast cancer treatment.

PMID:36821108 | DOI:10.1001/jamanetworkopen.2023.0569